Brush each edge of pastry with egg. Top with remaining circles, pressing edges together. (Make-ahead: Cover and refrigerate for up to 24 hours.) Brush top with egg. Cut steam vent in centre. Roll out scraps and cut out decorative shapes; arrange around steam vent. Brush decorations with egg. Bake in bottom third of 425°F (220°C) oven for 10 minutes. Reduce heat to 350°F (180°C); bake until pastry is golden and filling is bubbly, 30 to 35 minutes.